Vertical steps in isopters at hemiopic border - in normal and glaucomatous eyes.

Careful perimetry disclosed small steps in peripheral isopters corresponding to the vertical meridan in about 50% of normal eyes as well as eyes with glaucomatous field defects. Most steps were found inferiorly. The contraction of the isopter was always found on the nasal side of the field apart from a few of the glaucomatous eyes, all of which also showed central field defects. The findings suggest that no significance with regard to pathology can be attached to small peripheral steps at the vertical meridan provided that the temporal hemifield is the greater. Steps showing preponderance of the nasal half of the field, however, should arouse suspicion of an existing pathology. The reported observation as well as findings in the literature concerning function, anatomy and pathology suggest that the nasal hemiretina is dominant over the temporal one.